1. Field of the Invention
This invention relates generally to electrified musical instrument control circuitry. More particularly, it relates to an improved circuit system for pickup signal gain control, and control of related tonal effects.
2. Prior Art
Stringed musical instruments have been equipped with electrical waveform information pickups since at least the early 1930s. The signal from an instrument's pickup is usually amplified, and may be electrically modified, before reaching the sound reproduction device, for example, a speaker.
Multiple pickups on a single instrument have become common. When a string is plucked, a different position of the pickup relative to the vibration nodes of the string results in different signals generated by the pickup. Modern electric guitars usually have at least two pickups: a neck pickup and a bridge pickup. Multiple pickups may feed multiple distinct outputs, or be mixed into a single output audio signal.
Gain or attenuation controls to provide variable electronic modification to pickup signal level (volume), and tone (timbre) controls to modify signal waveform shape are currently in common use in electric instrument circuitry. For analog electrical signals, gain and tone controls are often controlled by knobs located on the body of the instrument, fitted to potentiometers that modify the signal. Switches may alter which pickup signals reach the output jack. A variety of external and internal effects modules are widely available to change signal timbre. A whammy bar produces vibrato by allowing the player to manually vary the tautness of the strings. The ability to vary an instrument's voice widely and conveniently is valued by many musicians.
A player's picking hand is generally the preferred actuator of signal controls, being dexterous and sensitive enough to make small adjustments. However, common prior-art methods of controlling the modification of the electrical pickups' signals prevent easy real time changes to their settings with the pick hand while picking. Knobs, switches, and sliders operated by the picking hand all require brief interruption of picking to adjust their settings. Some currently available modules therefore use foot controls, which are cumbersome, don't move with the guitar as the musician moves, and are operated by a relatively clumsy appendage. Some effects use mouth controls, which cannot be used while the musician is singing.
Additionally, prior-art controls typically vary only one signal at a time.
Further, the player has no convenient way to get information about the current position of a control in its travel range while picking.
Still further, in instruments that have two signal output channels carrying signals from different pickups, picking while rapidly panning between them has never before now been easy.
3. Previous Related Art Referenced
Dugas, in U.S. Pat. No. 4,481,854 (Nov. 13, 1984), recognizes a joystick's ability to simultaneously and independently control two ranges of signal characteristics. One axis of a first joystick is used to select the blend of signals drawn from each of two electric instrument pickups for combination, and its other axis is used to select tone filtering applied to the combined signal. One axis of a second joystick is used to attenuate the monaural signal, and its other axis is used to create a stereo effect by panning the signal between two outputs intended for two speakers. Neither joystick can be used while picking because their locations are too far from the active picking hand's position.
Since 1960, many Rickenbacker electric guitars and electric basses, for example models 360 and 4005, have been made with two output jacks. One is a mono output jack. The second, specialized, output jack is a two-channel jack that allows separate access to tone-filtered signals from the bridge treble pickup and the neck bass pickup (or neck and middle pickups as one channel in three-pickup models). It is designed to be cabled, with a two-channel stereo cable, to a separate Rickenbacker sound-control unit. When the two-channel jack is used, a knob located near the guitar's tail piece modifies the balance of the output pickup channel signals. The sound-control unit then selects and provides two signals at two monaural output jacks, allowing further independent processing of each signal.
The Rickenbacker guitars provide two attenuation control knobs not usable when the picking hand is in a normal picking position, each separately affecting one channel's signal. The balance knob is also not usable when the picking hand is in a normal picking position, and it can produce only a limited range of the attenuation combinations possible for the two channels.
Gibson also made guitars with a two-channel output jack option, for example, models ES-345 and ES-355. The newer Gibson B.B. King Lucille model has two single-signal jacks for separate access of its two channels. Gibson guitars provide multiple attenuation control knobs not usable from the picking hand's normal picking position, and each separate knob affects one pickup channel's signal.